Currently, there exists no noninvasive method of quantitating bypass graft flow reserve or the distribution of myocardial perfusion in man. In addition, there appears to be some deficiencies in the overall diagnosis of significant coronary artery disease inferred from stress-induced abnormalities in left ventricular contraction. Cine-CT allows for serial subsecond cardiac tomographic imaging using peripheral injections of iodinated contrast. Bypass graft flow and myocardial perfusion can be assessed from analysis of contrast clearance curves within a selected cardiac region of interest. Quantification of regional left ventricular contraction can be assessed from analysis of individual cardiac tomograms acquired at 17 frame/second. The University of Iowa is one of the few major research centers which has access to a cine-CT scanner. The proposed research is intended to validate the application of cine-CT to the quantification of regional myocardial perfusion, bypass graft flow reserve and studies of left ventricular contraction in the presence of physiologically significant coronary artery stenoses. The proposed research focuses on animal in vivo studies as well as studies in normal volunteers and patients with coronary heart disease. The principal investigator and colleagues have performed a number of preliminary studies essential to the proposed research. A study in 6 closed chest dogs has been performed to investigate the quantitation of myocardial perfusion by cine-CT. Empirically derived characteristics of left ventricular cavity and posterior papillary muscle contrast clearance curves have shown a significant correlation with regional myocardial perfusion as assessed by microspheres. Additional preliminary studies have also been performed to evaluate myocardial blood flow reserve in normal patients. Preliminary studies in the dog with an acutely placed aorto-coronary bypass graft have indicated that readily definable contrast clearance curve characteristics in the aorta and graft significantly correlate with graft blood flow rates. Preliminary studies of regional left ventricular contraction have been preformed in normal dogs and in a group of normal patients. These studies have revealed that normal left ventricular contraction at a given tomographic level occurs in a remarkably uniform fashion. The quantification by cine-CT of stress induced abnormalities in regional left ventricular contraction may well prove to be highly specific and sensitive for the diagnosis of significant coronary artery obstructions in patients.